12BH7

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PatOMalley

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12BH7
« on: 20 Jan 2010, 04:04 am »
Jim,  I saw it mentioned in a thread that you can swap in the 12BH7 in the Clarinet. Can you use it on the cornet2, as well?

amandarae

Re: 12BH7
« Reply #1 on: 20 Jan 2010, 05:11 am »

Here's from the man, himself....


Quote
Well, heater current is double for the BH7.  So you're probably running 5.9V or so on the heaters.  That might actually have something to do with the tonality.  It shifts the rp of the X7 at the same time.  You can always change the voltage dropping filter resistor in the heater circuit.  Or just leave it alone.  I doubt the tube is starved at these currents.  Probably last a long time.

I don't see any damage for trying.

jh

PatOMalley

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Re: 12BH7
« Reply #2 on: 20 Jan 2010, 12:38 pm »
That's good news.
Have you tried the 12bh7?

GRD

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Re: 12BH7
« Reply #3 on: 20 Jan 2010, 07:09 pm »
I did awhile back, dropping in a 12BH7 for the 12AU7 in my Cornet.  Sounded flat and a bit lifeless.  The right way to do it would be to adjust the heater voltage and probably reset the 12BH7 operating point (tweak the CCS).  Never explored it further.

PatOMalley

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Re: 12BH7
« Reply #4 on: 30 Jan 2010, 03:10 am »
Got my GE 12BH7's in the mail and plugged them into the Clarinet. No resistor change. Sound slowed down, kind of a drudge. I looked around and saw a post about making the 12BH7 the top tube in any totem so I plugged in an Amperex on the bottom and left the 12BH7 on top and it is nice.

More bass than before. No loss on top or in the mids. Seems more controlled. Very colorful, very powerful. Good to go.

Set in the Clarinet now is: Bendix, GE 12BH7, Amperex 12AU7.

Seeing what the 12BH7 does, how heavy it _can_ be I will try those steely sounding Sovteks or the vibrant gold pin Tung Sols with it in the Cornet2.

PatOMalley

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Re: 12BH7
« Reply #5 on: 30 Jan 2010, 04:01 am »
And in the Cornet2 the slow down the sound but tons of midrange texture and color.
I will let them burn in some more to see if they open out a little. If not I will change the resistor ion the Cornet2 - lots of promise.

These 12BH7s replaced Amperex mid 60s Holland 12AU7s which have been my favorite sounding au7s in my little lot of tubes. The Amperex are more lively but lack the bass authority, control and [believe it or not] midrange color and presence of these GE 12BH7s.



PatOMalley

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Re: 12BH7
« Reply #6 on: 30 Jan 2010, 04:11 am »
So what exactly do you change to accommodate the 12BH7 in the Cornet2 and Clarinet?
TIA, amigos.

PatOMalley

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Re: 12BH7
« Reply #7 on: 30 Jan 2010, 06:04 am »
Been at this for a several few hours and on second thought I think I will just keep the 12BH7 in the Clarinet. Don't want to mess with the RIAA by way of locking in another tube that I need to get the iron out to reverse.

I like the sound of the NOS 5751s and Amperex Holland 12AU7 anyway. And after a while there does seem to be a fisheye lenz using the BH7. Mids are great but the sound is too slow, almost as if it drops back 2% in pitch.

Bill Epstein

Re: 12BH7
« Reply #8 on: 30 Jan 2010, 12:18 pm »
Quote
after a while there does seem to be a fisheye lenz using the BH7

I had a similar experience with substituting Amperex 7062 for my favorite Sylvania 5965 drivers, both of the 12AV7 family, in my 45 amp. At first I loved the additional detail and dynamics, then it got to be too much of a good thing. Now I only run 5965s.

hotrod

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Re: 12BH7
« Reply #9 on: 1 Feb 2010, 10:56 pm »
 Concerning other possible tubes that can be used in the Clarinet,what would have to be done in order to use an E80CC?I know in some cases its a direct replacement but I don't know enough about circuit design to know if it is acceptable with the Clarinet/Cornet.
 Any info would be appreciated.